The sheared vec B that converges towards the PIL is a characteristic motion to create a BP. This pattern can also be seen in [1]}. It is due to the summed effects of: (i) the shear that creates a BP with vec B in the negative polarity pointing towards the positive polarity; and (ii) the asymmetry of the photospheric flux concentration with a stronger positive polarity (in the model and observations) which is due to the magnetic pressure pushing all the fields towards the (weaker) negative polarity. Hence it is leading to some sheared vector within the positive polarity to point towards the negative polarity. These two effects lead to the convergence.
polarity. These two effects lead to the convergence. The swirling motions visible at both ends of FR are well-represented by vec B, which display similar angles and similar spatial gradients at the edges of the swirlings, which
separate the swirling vec B from the surrounding magnetic field that has more potential, that is, exhibiting more radial from the center of the magnetic polarity. For example, this separation is visible at the top right in Figure REF  (a and c) in the positive polarity, where radial vectors are close to turning vectors to the left, and at the bottom of the negative polarity, there is a similar separation between radial vectors and vectors turning to the left. This kind of separation is reminiscent of a QSL, just as in the MHD models ([2]}; [3]}). Moreover,
those swirls correspond exactly to the footpoints of sigmoidal field lines, even though they are not visible in the extreme ultraviolet (EUV).
Finally, the similarity of all these characteristics structures
(e.g. BP, QSL, sigmoidal field line) between the MHD models and our observations leads us to infer the existence of a FR in the immediate vicinity of the jet.
